Mewtwo has no official special moves in Super Smash Bros for Wii U/3DS, but you can hackily achieve them through the use of Miis. In order to do it, you have to download a Mii not created on your system, then select it for play, deselect it, and select Mewtwo. Mewtwo inherits that Mii's custom moves, but since this isn't supposed to happen things get pretty glitchy.